无法将类型 'System.Collections.Generic.List' 隐式转换为 'System.Collections.Generic.List<Model.Room

Question

尝试 return 实体选择字段但出现错误

我的界面

public  interface IRoomRepository
{
    List<Room> All();

    Room Get(int id);

    Room Add(Room obj);


    void Delete(Room obj);

    void Update(Room obj);
}

我的存储库和我实现了 IRoomRepository

public List<Room> All()
    {
        using (HotelEntities db = new HotelEntities())
        {
            var result = from room in db.Rooms
                         select new
                         {
                             room.RoomNumber,
                             room.Id,
                             room.RoomType
                         };
            return result.ToList();
        }
    }

出现以下错误

无法将类型 'System.Collections.Generic.List<>' 隐式转换为 'System.Collections.Generic.List'

编辑

房间模型Class

namespace Model
 {
    using System;
    using System.Collections.Generic;

    public partial class Room
    {
        public int Id { get; set; }
        public string RoomNumber { get; set; }
        public Nullable<int> RoomTypeId { get; set; }
        public Nullable<int> RoomStatusId { get; set; }

        public virtual RoomStatus RoomStatus { get; set; }
        public virtual RoomType RoomType { get; set; }
    }
}

Answer 1

您必须明确地创建 Room 对象。new {} 创建无法转换为 Room 的匿名对象。假设属性名称相同，以下应该有效

public List<Room> All()
{
    using (HotelEntities db = new HotelEntities())
    {
        var items = from room in db.Rooms
                     select new
                     {
                         room.RoomNumber,
                         room.Id,
                         room.RoomType
                     }.ToList();

        var result = items.Select(i=>
                       new Room  {
                         RoomNumber = i.RoomNumber,
                         Id  = i.Id,
                         RoomType  = i.RoomType
                     }).ToList();
        return result;
    }
}

无法将类型 'System.Collections.Generic.List' 隐式转换为 'System.Collections.Generic.List<Model.Room

Cannot implicitly convert type 'System.Collections.Generic.List' to 'System.Collections.Generic.List<Model.Room

c#

linq-to-entities

entity-framework